The disappearing island

Sometimes I don't understand my fellow humans at all.

Take, for example, our habit of drawing imaginary lines all over the place and then pretending those lines should have an impact on what can do.  Over here, you have to follow one set of rules; walk ten meters to the west and cross an invisible line some random person made up, and you have to follow a completely different set of rules.  You want to purchase liquor, own a gun, marry someone of the same sex, gamble, get decent health care or a good education?  Whoa, you first better figure out where the lines are and make sure you're on the right side!  In order to cross some lines (legally, at least) you have to have a specific little booklet and let a grim and humorless person stamp it first.  Try to get across without a booklet and stamp, and boy, are you in trouble.  In fact, some people take these invisible lines so seriously they'll kill anyone who tries to cross.

This kind of behavior may well explain why the aliens take one look at Earth and then warp right the fuck out of the quadrant.

One of the weirdest examples of this phenomenon has to do with an on-again, off-again island in the central Mediterranean, about halfway between Tunisia and the island of Sicily.  You probably know this is a tectonically-active region -- Sicily is the home of Mount Etna -- so there are a number of small volcanic islands and seamounts dotted around the place.  One of these is called (depending on whom you ask) Empedocles Seamount or Graham Island or Île Julia or Isola Ferdinandea.

The reason for the multiple names is that prior to 1831 it had been a submarine volcano, on the order of six meters below sea level at lowest tide.  But then it erupted (as volcanoes are wont to do) and suddenly the peak of the seamount was above sea level.

That's when the fun began.

In August of that year, British sea captain Humphrey Fleming Senhouse saw the newly-formed island (at that point pretty much just a bunch of hot rocks barely poking up out of the water), and in the fine old British tradition of spotting a place and saying "Mine!", claimed it for the British crown.  He named it Graham Island after Sir James Graham, First Lord of the Admiralty.  The problem was, French geologist Constant Prévost was also nearby studying the volcanoes in the region, and when the island appeared he thought King Louis Philippe I of France might fancy having a bunch of rocks, so he claimed it for France (and named it Île Julia, supposedly because it appeared in July).  But it wasn't long before the Sicilians, who after all were nearest to the place, said, "The hell you say" and claimed it for their own, renaming it for a third time Isola Ferdinandea (after King Ferdinand II of the Kingdom of Two Sicilies).

As far as I know, the Tunisians decided to leave well enough alone and didn't get involved.

A page out of Constant Prévost's field journal, showing the eruption of whatever-its-name-is [Image is in the Public Domain]

Diplomatic wrangling ensued.  One of of the concerns surrounded whether this was a sign of increasing volcanism, and if it might ultimately link up Sicily with Tunisia, and where would they draw the invisible lines if that happened?  The British were adamant that they wanted it for its strategic location, and drew up plans for building a naval base there.  The French, more luxury-minded, started thinking about a holiday resort.  The Sicilians mostly just said the Italian equivalent of "But... but it's ours," to no particular effect.

It's uncertain what the ultimate outcome of the dispute would have been, because within a few months it became obvious that Graham/Julia/Ferdinandea Island was shrinking.  It turned out that the eruption had mostly produced tephra -- a loose, porous, crumbly rock that doesn't withstand erosion.  Like, at all.  In January 1832 it was reported as barely visible, and by that summer the island had disappeared entirely.  The French, British, and Sicilians all sort of kicked at the dirt and said, "Awww, rats" in an embarrassed sort of way, and then toddled off to look around for other arbitrary and pointless things to fight about.

So at the moment it's back to being Empedocles Seamount, with its peak about eight meters below water level.  Amazingly, though, the dispute is still bugging people.  In November of 2000, some Sicilian divers went down and planted a marble plaque with a Sicilian flag on the top of the seamount, with the idea being if it ever surfaces again the Sicilians will already have laid claim to it.  The plaque has an inscription that reads, "This piece of land, once Ferdinandea, belonged to and shall always belong to the Sicilian people."

Within six months, the combination of waves and tectonic activity fractured the plaque into twelve pieces.  

The whole affair made me think about the quote from Voltaire: "God is a comedian playing to an audience which is afraid to laugh."

But more to the point: is it just me, or is this kind of behavior seriously weird?

I think we accept it just because it's so common, but really, I find myself much more in sympathy with a lot of the Indigenous peoples, who when they first ran into Europeans (whose capacity for invisible line-drawing is second to none) couldn't even understand what the invaders meant when they said "this land is mine now."  The land was here long before you were born, and will still be here long after you're dead.  What does it mean to say it's "yours"?  And it's more bizarre than that when you start factoring in things like mineral rights.  Okay, legally I own 3.5 acres of land.  Do I own what's underneath it?  If so, how far underneath?  Do I own a gradually narrowing conical chunk of material extending all the way to the Earth's center?

What the fuck would that even mean, that I "own" something that I'll never see, never touch, and is in fact physically impossible to reach?

I dunno.  Apparently it makes sense to other people, so maybe I'm the weird one.  All I know is when I think about things like this, and other stuff we argue incessantly about -- like what comprises ninety percent of politics -- I'm hoping the aliens will at least slow down their passage by Earth long enough to pick up a passenger.

****************************************

A flood of mythic proportions

Ever heard of the Zanclean Flood?

If not, you definitely should, because it was pretty stupendous.

At some point during the late Miocene Epoch, a combination of tectonic activity and sea level drop brought the level of the Atlantic Ocean below the Gibraltar Sill, the range of (now underwater) mountains that crosses the Strait of Gibraltar, connecting Spain to Morocco.  When that happened, the Mediterranean Sea was cut off from the Atlantic, and received its only influxes of water from rainfall and the input from rivers (including the Rhone, Nile, Po, and Tiber Rivers).

At that point, the evaporation from the hot, dry winds off northern Africa and southern Europe occurred at a greater rate than the influx of water, and the Mediterranean began to dry up.  Eventually it split into two extremely saline parts, separated by another sill across the Straits of Sicily, each of which had a water level way below that of the rest of the Earth's oceans.

Well, in geology nothing is constant but change.  About 5.33 million years ago, tectonic activity, this time coupled with a sea level rise, eventually breached the barrier of the Gibraltar Sill, creating a waterfall.

But this wasn't just a waterfall.  This was a freakin' HUGE waterfall.

Geologist Daniel García-Castellanos, of the Spanish National Research Council, has done a tremendous amount of research into the Zanclean Flood and the events that led up to it, and has estimated that the Gibraltar Sill Waterfall, at its greatest, was a kilometer tall and was pouring two hundred million cubic meters of water into the Mediterranean Basin per second.

For reference, this is a thousand times more water than the Amazon River moves during the rainy season.

Artist's conception of the western Mediterranean just as the Zanclean Flood was beginning [Image licensed under the Creative Commons Paubahi, Etapa4, CC BY-SA 3.0]

So the Mediterranean began to refill, reaching increases in level of ten meters per day.  This kind of water flow created erosion like you can't even imagine, blowing enormous boulders over the Sill and down into what is now the western Mediterranean.  Anything in the water's path was drowned.  The sudden refilling of the basin drastically changed the climate, cooling what had been a blast-furnace of a desert (think Death Valley but much, much bigger).

All things considered, one of the most dramatic geological events ever.

One of the difficulties of studying it, though, is that all of the evidence is currently underwater.  But now García-Castellanos, again working with a team from the Spanish National Research Council, has found what might be the smoking gun for the Zanclean Flood.

Using seismic reflection profiles, García-Castellanos and his team have found massive piles of sediments that were apparently deposited over a very short period of time, right where you'd expect to find the talus pile of the Gibraltar Sill Waterfall.  It's enormous -- as you might expect -- 163 meters thick, 35 kilometers long, and 7 kilometers wide, extending from the Sill down into the depths of the Alborán Sea, the very western bit of the Mediterranean.  "The identified sediments are compatible with a megaflood event refilling the Mediterranean Sea through the Strait of Gibraltar," García-Castellanos said.  "It's an enlarged body deposited in the protected area at the lee side of a submarine volcano."

However, as befits a good scientist, García-Castellanos has invited other geologists and seismologists to examine the data and see if his conclusions are valid.  "Ten years after publishing the first observations that were related with the Zanclean Flood we are still finding new evidence to sustain it, but it is not conclusive," he said.  "All of the evidence that has been summarized in this article may have other possible interpretations and, before convincing the scientific community it will be necessary to have other studies that consider the hypothesis from other angles."

But however it eventually falls out, the refilling of the Mediterranean must have been something to see.  From a safe distance.  The geological processes of the Earth are often unsubtle, and their power makes me feel very, very small, but even looking at it from a geologist's perspective, this one must have been spectacular.

Feeling humbled by the universe is not necessarily a bad thing.  We humans have a way of getting cocky and thinking we're in charge of things.  Looking back in geological history, though, one very quickly realizes our fragility in the face of forces far, far more powerful than anything we've been able to devise -- and that our continued survival on Earth is in no sense guaranteed.

*********************************

This week's Skeptophilia book of the week is both intriguing and sobering: Eric Cline's 1177 B.C.: The Year Civilization Collapsed.

The year in the title is the peak of a period of instability and warfare that effectively ended the Bronze Age.  In the end, eight of the major civilizations that had pretty much run Eastern Europe, North Africa, and the Middle East -- the Canaanites, Cypriots, Assyrians, Egyptians, Babylonians, Minoans, Myceneans, and Hittites -- all collapsed more or less simultaneously.

Cline attributes this to a perfect storm of bad conditions, including famine, drought, plague, conflict within the ruling clans and between nations and their neighbors, and a determination by the people in charge to keep doing things the way they'd always done them despite the changing circumstances.  The result: a period of chaos and strife that destroyed all eight civilizations.  The survivors, in the decades following, rebuilt new nation-states from the ruins of the previous ones, but the old order was gone forever.

It's impossible not to compare the events Cline describes with what is going on in the modern world -- making me think more than once while reading this book that it was half history, half cautionary tale.  There is no reason to believe that sort of collapse couldn't happen again.

After all, the ruling class of all eight ancient civilizations also thought they were invulnerable.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]